1
Chapter 1
Basic DC Circuits
2
Objectives
Distinguish between dc and ac and
discuss some of the basic properties of
each.
State and describe the basic circuit
variables including charge, voltage,
current, power, and energy.
Define resistance and conductance and
show the schematic symbol.
3
Objectives
State the properties of the ideal voltage
source and ideal current source models
and show their schematic symbols.
State and apply Ohm’s law.
Discuss voltage and current
measurements and how they are made.
State and apply Kirchoff’s voltage law.
State and apply Kirchoff’s current law.
4
Objectives
Determine equivalent resistance using
series and parallel combinations.
Analyze a single

loop (series) circuit to
determine all the variables.
Analyze a single node

pair (parallel) circuit
to determine all the variables.
State and apply the voltage divider rule.
State and apply the current divider rule.
5
1

1 DC Circuit Variables
Resistance “
R”
(Ohm:
Ω
)
Voltage
“V”
(Volt: V)
Current
“I”
(Ampere: A)
Power
“P”
(Watt: W)
Energy
“W”
or
“E”
(Joules: J, or watt

hour)
6
Comparison of a DC Voltage and an AC
Voltage
7
Conventional Current Flow in Opposite
Direction to Electron Flow
8
Voltage Between Two Points in a Circuit
9
Schematic Symbols for an Ideal Voltage
Source and a Battery
10
Schematic Symbol for an Ideal Current
Source
11
Schematic Symbol for a Resistance
12
Illustration of a Short Circuit and an Open
Circuit
13
1

2 A Very Simple DC Circuit
14
Different Types of Ground
15
Simple Circuit Redrawn with Ground
Symbols
16
1

3 Measuring DC Circuit Variables
Ohmmeter
Voltmeter
Ammeter
Wattmeter
Multi

meter
17
A Voltmeter is Connected Between Two
Points in a Circuit Across Which the
Voltage is to be Measured
18
An Ammeter is Connected Within the
Branch for Which Current is to be
Measured
19
1

4 Power and Energy
Energy:
work performed,
or
capacity to
perform work
Power:
rate of change of energy
20
Reference Directions for Power Delivered
21
Reference Directions for Power Absorbed
1

5 Kirchoff’s Laws
22
Kirchoff’s
Voltage Law:
algebraic sum of all
voltages around a closed loop = zero
Kirchoff’s
Current Law:
algebraic sum of all
currents into a node = zero
23
A Loop Used to Illustrate Kirchoff’s
Voltage Law
24
Illustration of Kirchoff’s Current Law at a
Node
25
Circuit of Example 1

8
26
Circuit of Example 1

9
27
1

6 Equivalent Resistance
Series connected resistors
Resistances add
Equivalent resistance greater than largest
resistor
Parallel connected resistors
Conductances
add
Equivalent resistance less than smallest
resistor
Series and parallel combinations
28
Resistances in Series and the Equivalent
Single Resistance
29
Resistances in Parallel and the
Equivalent Single Resistance
30
Circuit of Example 1

10
31
Reduction of the Circuit of Example 1

10
32
1

7 Single

Loop or Series Circuit
One current (shared by all circuit’s
components)
Multiple voltages:
Voltage drop (across resistance)
Voltage rise (across sources)
Obey
Kirchoff’s
Voltage Law
Series circuit:
Voltage Divider Rule
33
Representative Single

Loop (Series)
Circuit
34
Circuit of Example 1

11
35
Circuit of Example 1

12
36
1

8 Single Node

Pair or Parallel Circuit
One voltage (drop or rise) shared by all
circuit’s components
Multiple currents:
Branch currents
Obey
Kirchoff’s
Current Law
Parallel circuit:
Current Divider Rule
37
Single Node

Pair (Parallel) Circuit
38
Representative Parallel Circuit with
Current Sources
39
Circuit of Example 1

13
40
Circuit of Example 1

14
41
1

9 Voltage and Current Divider Rules
VDR
V
x
= V
T
* R
x
/ R
T
IDR
I
x
= I
T
* R
T
/ R
x
42
Circuit Used to Illustrate the Voltage
Divider Rule
43
Circuit Used to Illustrate the Current
Divider Rule
44
Circuit of Example 1

15
45
Circuit of Example 1

16
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